The present invention relates to a battery pack including a polymer battery.
A polymer battery is manufactured by laminating sheathing films on both surfaces of an electrode and airtightly connecting the sheathing films at a circumference of the electrode. The polymer battery with this structure has an advantageous feature in that the polymer battery can be made thinner and bigger as compared to a battery in which an electrode is inserted in a metal sheathing case. However, the polymer battery has a drawback due to the lack of the metal sheathing case. Namely, since the strength of the sheathing film is weaker than the metal case, a front surface of the polymer battery is more likely to be damaged. In order to solve this adverse effect, there has been developed a battery pack in which a polymer battery is encased in a sheathing case as disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 11-111250, the content of which is incorporated hereinto by reference. In the battery pack disclosed in this publication, as shown in FIG. 1 and FIG. 2, a polymer battery 21 is stored in upper and lower cases 22. The upper and lower cases 22 are manufactured by inserting metal plates 24 into plastic frames 23.
In the battery pack with the aforementioned structure, although both surfaces of the polymer battery can be protected by the metal plates, there is a drawback in that the overall battery pack becomes thick. Since it is important that the polymer battery can be made thin, if the overall thickness is increased, there is the drawback of losing the valuable and excellent advantageous feature thereof. Namely, among thin batteries manufactured by inserting electrodes into metal sheathing cases, for example, lithium ion rechargeable batteries or the like, there has been developed a thin battery having a thickness of only 3.8 mm. In view of the foregoing, it is especially important for the battery pack with the polymer battery to be made as thin as possible.
Further, it is also important for the battery pack with the polymer battery to provide solid output terminals while being made thin as a whole. When the battery pack is mounted on an electrical device, terminals of the electrical device side are elastically pressed against the output terminals, so that a solid structure is required so as not to be deformed. Since the polymer battery has the structure in which lap sections of the sheathing films are bonded at the periphery of the electrode, it is difficult to securely hold the output terminals. Especially, it is difficult to solidly hold the output terminals while the battery pack is made thin. This is because the strength of the lap section is not made sufficient if the output terminals are disposed at the lap section in order to make the battery pack thinner.
The present invention has been developed in order to solve the aforementioned drawbacks. An important object of the present invention is to provide a battery pack including a polymer battery, in which output terminals can be securely supported while the overall battery pack is made thin, and the strengths of both surfaces of the battery pack can be improved.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.